Engineering ToolBox - Resources, Tools and Basic Information for Engineering and Design of Technical Applications!

This is an AMP page - Open full page! for all features.

Water Supply - Calculating Demand

Calculating expected demand of water supply in service lines

Sponsored Links

The total theoretical demand for a water supply system can easily be calculated by adding known maximum demand for all fixtures in the system. Due to the nature of intermittent use this will unfortunate add up to unrealistic demands for the main supply service lines. A realistic demand for a supply system will always be far less than the total theoretical demand.

Expected demand in a water supply system can be estimated as

qet = qnl + 0.015 ( Σqn - qnl  ) + 0.17 ( Σqn - qnl  )1/2                                           (1)

where

qet = expected total water flow (l/s)

qnl = demand of largest consumer (l/s)

Σqn = total theoretical water flow - all fixtures summarized (l/s)

Note that minimum expected total water flow can never be less than the demand from the largest fixture. This equation is valid for ordinary systems with consumption patterns like

  • homes
  • offices
  • nursing homes
  • etc.

Be aware when using the equation for systems serving large groups of people where the use is intermittent, like in 

  • hotels
  • hospitals
  • schools
  • theaters
  • wardrobes in factories
  • etc  

For these kind of applications, like a wardrobe, it is likely that all showers are used at the same time. Using the formula blindly would result in insufficient supply lines.

Example - Main Water Supply to a Nursing Home

If the theoretical demand from all fixtures in a nursing home adds up to 50 l/s and the larges fixture requires 0.4 l/s, the expected water supply demand can be estimated like

 qet = (0.4 l/s) + 0.015 ((50 l/s) - (0.4 l/s)) + 0.17 ((50 l/s) - (0.4 l/s))1/2

    = 2.3 (l/s)

Total Theoretical Water Flow and Expected Flow

Expected demand for a supply system at different total theoretical demand can based on the formula above be expressed as

Total Theoretical Demand Summarized
(liter/s)

Load Calculator!
Expected Demand
(liter/s)

Load Calculator!
0.2 0.2
0.8 0.4
1.6 0.5
4.0 0.6
8.0 0.85
15 1.1
20 1.5
30 1.8
40 2.1
65 2.8
70 2.9
100 3.7

The maximum fixture load is 0.2 liter/s.

Sponsored Links

Related Topics

Related Documents

Sponsored Links

Share

Search Engineering ToolBox

  • the most efficient way to navigate the Engineering ToolBox!

SketchUp Extension - Online 3D modeling!

Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your Sketchup model with the Engineering ToolBox - SketchUp Extension - enabled for use with the amazing, fun and free SketchUp Make and SketchUp Pro .Add the Engineering ToolBox extension to your SketchUp from the Sketchup Extension Warehouse!

Privacy

We don't collect information from our users. Only emails and answers are saved in our archive. Cookies are only used in the browser to improve user experience.

Some of our calculators and applications let you save application data to your local computer. These applications will - due to browser restrictions - send data between your browser and our server. We don't save this data.

Google use cookies for serving our ads and handling visitor statistics. Please read Google Privacy & Terms for more information about how you can control adserving and the information collected.

AddThis use cookies for handling links to social media. Please read AddThis Privacy for more information.

Topics

Unit Converters

Temperature

oC
oF


Load Calculator!

Length

m
km
in
ft
yards
miles
naut miles


Load Calculator!

Area

m2
km2
in2
ft2
miles2
acres


Load Calculator!

Volume

m3
liters
in3
ft3
us gal


Load Calculator!

Weight

kgf
N
lbf


Load Calculator!

Velocity

m/s
km/h
ft/min
ft/s
mph
knots


Load Calculator!

Pressure

Pa (N/m2)
bar
mm H2O
kg/cm2
psi
inches H2O


Load Calculator!

Flow

m3/s
m3/h
US gpm
cfm


Load Calculator!

9 25

This website use cookies. By continuing to browse you are agreeing to our use of cookies! Learn more